Epidemiologist Dr Michael Baker is calling for increased restrictions on people entering New Zealand, as Covid-19 surges overseas.
London and New South Wales are both facing increasing pressure due to the virus.
New South Wales, which had until now been mostly free of the virus, has an outbreak in Sydney's Northern Beaches suburb, which saw 44 cases reported yesterday, bringing the state's total to 68.
Meanwhile in the United Kingdom, a new strain of the virus has been found to be significantly more infectious.
It's has forced Prime Minister Boris Johnson to put London into lockdown shortly before Christmas.
Baker said it's not abnormal for new strains of a virus to develop as they are always under evolutionary pressure.
"If one [strain] is more infectious than others, it will create more viruses in the next generation, and so on so that strain will start to become dominant. This is the way these viruses go."
He said in the wake of those troubles it would be best to add more requirements for those entering New Zealand from the UK, including a small period of isolation before leaving, as well as proof they have tested negative.
"Every time we get an infected person going into an MIQ facility in New Zealand, it increases the risk of outbreaks."
He said Australia should also be looking to turn down the tap of arrivals too.
"It's going to be months before we have enough vaccine coverage in Australia and New Zealand to really limit transmission. In this dangerous period, I think we need I think this extra step."